GMT

Railway Time

We are indebted to Peter E Davies of
www.carnforth-station.co.uk
for permission to reproduce this article on Railway Time which explains the
advent of Greenwich Mean time.

For many centuries, there was little need for time to be accurately
measured. The transition from day to night, the movement of the moon and
the changing of the seasons were enough to measure large units of time,
and for most people, the passing of the sun through the sky was adequate
to indicate sunrise, sunset and mid-day.

For those who needed to
order their daily time more accurately, such as monks or scientists, they
used a combination of crude measuring devices, such as sand timers or
burning candles, or, if the sun was shining, the shadow of a sundial.

The mechanical devices in use to measure time were highly
unreliable, a candle may burn erratically, depending on draughts, damp in
the air, and its physical construction, sand timers were only slightly
more accurate.

The Sun was the most accurate way of measuring time,
but although the Greeks had discovered a way of calibrating a sundial to
show equal hours, most sundials were of a simple type that only divided
the day up into a unequal parts.

The Sun itself is not a very
accurate way of measuring simple time. Because of the way the Earth
circles the Sun, the apparent time of mid-day, when the Sun is at its
highest in the sky, may vary up to 16 minutes early or late, from the real
time, depending upon the time of year. This cyclic variation away from
true time also means that the solar day is not exactly 24 hours long, but
becomes longer, or shorter, by a small amount each day, depending where in
the cycle the Earth is.

The Earth rotates once every 24 hours, and
so places to the East start their day sooner, than places to the West.
Mid-day in one place takes place at the same instant as sunrise, or
sunset, at other places on the Earth. Across Britain there is a difference
in time of approximately half an hour, from the Eastern to the Western
extremities.

Until late into the 18th century watches and clocks
were mostly for the rich, and their inaccuracy made the difference between
clock and sundial less obvious.

From 1792, in England, it became
normal to use local mean time, rather than apparent time from a
sundial.

Whilst travel and communications were slow, these local
time differences were of little importance, and most towns and cities in
Britain used local time. By the 18th Century horse drawn coaches were
taking mail and passengers across Britain, and the guards on these coaches
carried timepieces, so that they could regulate the arrival and departure
times. Because of the local time differences across Britain, these
timepieces were adjusted to gain about 15 minutes in every 24 hours, when
travelling west - east, to compensate for the local time differences. (and
of course adjusted to lose 15 minutes in 24 hours when
returning)

In the early part of the 19th century, communications
started to be significantly improved, the railways started to be
constructed, and "Galvanic Communication" (Telegraph by wires) started to
become common.

To many aspects of life, accurate time was becoming more and
more essential, and the usage of local time became a great inconvenience. A
telegraph message wired from London, early Saturday morning, might arrive
instantaneously in Dublin late Friday night. Two babies born at the same instant
in time, but in different east / west parts of the country might be officially
born on two different days, with possibly quite serious legal implications for
inheritances

By the
1840's there were at least three organisations which suffered
inconveniences because of the use of local times - The railways, the
telegraph companies, and the Post Office.

In June 1836, John Henry
Belville, who was employed at the Greenwich Observatory in London, started
making a weekly visit to the principal chronometer makers in London , he
took a pocket chronometer with him, set to Greenwich time.

In
November 1840, the Great Western Railway ordered that London time should
be used in all its timetables, and at all its stations.

In 1845
the Liverpool and Manchester Railway company unsuccessfully petitioned
Parliament, to ask that a single uniform time be used for all ordinary and
commercial purposes.

In January 1846, the North Western Railway
introduced London time, to their station at Liverpool and
Manchester.

On 22nd September 1847, the Railway Clearing House
recommended that every railway company in Britain adopt Greenwich time at
their stations, as soon as possible.

In 1st December 1847, the
London and North Western, and the Caledonian Railway both adopted London
time.

Bradshaws Railway Guide for January 1848 list the London and
south western, London and North western, Midland, Chester and Birkenhead,
Lancaster and Carlisle, East Lancashire and the York and North Midland
railways as all keeping Greenwich time.

The Great Western, South
Eastern and the Caledonian were also keeping Greenwich time.

On 17th
February 1852, the installation of telegraph lines between the
Greenwich Observatory, and Lewisham station was completed, by August time
signals were sent on a regular basis from the Greenwich Observatory, to
London Bridge station, and onwards from there through the railways
telegraph system, and also through the Central Telegraph Station of the
Electric Time Company in Lothbury, for further distribution all over the
country.

On 30th October 1852 the following instruction was
passed to the South Eastern Railway. (A similar order went to the Great
Western, and probably to other railways as well.

The Astronomer Royal has
erected Shepherd's Electro-Magnetic Clock at the Royal Observatory,
for the transmission of Greenwich Mean Time to distant
places.

On and after November 1st, the needle of your
Instrument will move to make the letter N precisely at . . o'clock
every day.[Different stations received time-signals at different
hours.]Abstain from using the instrument for Two Minutes before
that time. Watch the arrival of the signal; and make a memorandum,
for your own information, of the error of your Office Clock.You
are at liberty to allow local Clock and Watch Makers to have
Greenwich time, providing such liberty shall not interfere with the
Company's service and the essential privacy of Telegraph Offices,
and the business connected there with.Engineer and
Superintendent of Telegraphs

To
Mr.........................................................................Station.

From the start, some railway companies used "London" time, while others
used local time. Trains travelling east to west appeared to be travelling
slower than the return journey, west to east, which caused may problems
with timetabling. At stations of Railway Companies that used London time,
the Railway time could be quite different to local time, with all sorts of
problems of missed trains and connections, in some places, there were even
two minute hands on the public clocks, one showing local, the other
showing London time.

On 1st June 1880 the Statutes (Definition of
time) Bill, was read for the first time in the House of Commons, and
received the Royal Assent on 2nd August 1880.

At last, a "standard"
time was in use across the whole of Britain, and there was no more
confusion caused by local time.